This invention relates to a welding torch and more particularly to an electric arc welding torch having a consumable electrode.
The present invention, while of general application, is particularly well suited for use with welding torches of the type which produce the weld under an inert gaseous atmosphere. It is known that in the welding process practiced with this type of torch, called MIG welding, the transfer of molten metal in the arc usually occurs in the form of fine globules, some of which rise upwardly and are then thrown in the direction of the torch. The globules exhibit a tendency to settle on the lower portion of the torch adjacent the outlet orifice for the inert shielding gas, to form an agglomerate of strongly adhering particles which pose the danger of plugging the outlet orifice and thereby obstructing the passage of the shielding gas. Other globules frequently penetrate into the interior of the torch, that is to say, well into the shielding gas chamber. These latter globules settle on the walls of the chamber in the form of particles which do not adhere so tightly but in time nevertheless interfere with the passage of the shielding gas. Moreover, the particles may establish an electrical path between the components of the torch in contact with the high voltage electrode and those components which normally are insulated from the electrode. The resulting short circuit would seriously impair the welding operation and very likely damage the torch.
Heretofore, attempts to resolve the particle agglomeration problem in some cases utilized a part capable of translatory motion and acting as a scraper adjacent the outlet orifice for the inert gas. However, this system resulted in only a very crude cleaning job in the discharge portion of the torch and was of little value in the removal of particles which penetrated into the interior of the shielding gas chamber.
Other attempts to resolve the problem entailed some form of blower system, for example, a compressed-air blower, in the interior of the shielding gas chamber. To be effective, such a system required a source of compressed gas under relatively high pressure (on the order of 12 bars). Although the system worked reasonably well for lightly adhering particles, it had little or no effect on the strongly adhering agglomerates forming at the nozzle end of the torch.